System of electric distribution



REcMS/Iw/VMA A. E. ANDEREON SYSTEMS OF ELECTRIC DISTRIBUTION Filed March 31, 1943 Figl.

P170485 HESPOIVS/VE 49524) Sept. 18, 1945.

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Patented Sept. 18, 1945 SYSTEM or nnaormc ms-rnmurros Arvld E. Anderson, Baverl'ord Township, Delaware County, Pa assignor to General Electric Company, a corporation of New York Application March 31, 1948, Serial No. 481,315

18 Claims.

My invention relates to systems of electric distribution and particularly to such a system in which two alternating current circuits are ara ed to be interconnected when one of the circuits is deenergized and the other is energized and, also, when both of the circuits are simultaneously energized and a predetermined phase and masnituderelation exists between the voltages of the two circuits.

My invention relates particularly to an arrangement ior automatically controlling the phase and magnitude relation the voltages 01' two alternating current circuits by means of suitable adjustable transiorming means so that the voltages of the two circuits can be brought into the proper phase and magnitude relation to prevent excessive circulating currents from flowin: between the two circuits when the circuit breaker interconnecting the two circuits is closed.

My invention will be better understood from the following description when taken in connection with the accompanying drawing, Fig. l of which illustrates a system or electric distribution embodying my invention, Fig. 2 01 which illus trates a modification of the embodiment shown in Pig 1. and Fig. 3 of which is an explanatory vector diagram, and the scope of my invention will be pointed out in the appended claims.

Referring to Fig. l or the accompanying drawing, I have shown a system oi alternating current electric distribution comprisin a load circuit which is connected to a winding 2 of a power transformer 3, a,second winding l of which is connected by means of a suitable circuit breaker I to an alternating current supply circuit 6. The load circuit I is also arranged to be energized with current from another source of current, such as I, which is maintained in synchronism, in any suitable manner well known in the art but not shown in the drawing, with the source or sources that supp y current to the supply circuit I. Due to system conditions, such as the diflerent line impedances between the various sources and the point in the load circuit where circuit breaker I is located, it will be apparent to one skilled in the art that the circuit voltages on the opposite sides 01' the circuit breaker I when it is open may be out or phase and of unequal magnitude although the sources are in synchronism. Unequal loading or diilerences in loading characteristics or the. sources will also contribute tothisresult.

Inorder to simplii'ythe discl0sure,1have shown thesupplycircuitlandtheloadcircuitlas single phase circuits, but it will be obvious that my invention is applicable to circuits 0! any number oi phases.

For changing the ratio 0! voltage transiormaticn of the power transformer 3, I have shown a tap changing mechanism 9 having a movable contact In which is adapted to be moved by means of a reversible motor ii into engagement with a number of taps it provided on the transformer winding 2. For regulating the phase relation of the voltages of the supply circuit 8 and the load circuit i, I provide in one of the circuits an ad Justable transformer i3 0! a suitable type to produce a voltage of variable magnitude which is displaced in phase relative to the voltage iro pressed across the circuit i by the transformer 3 or the other sources that may be supplying current to the circuit. Such an adjustable transformer may be or the tap changing type, similar to that shown in connection with the power transiormer 3 or or the induction regulator type. In the particular embodiment shown in Fig. l, the adjustable transformer 13 is shown as an induction regulator having one winding it connected in series relation with the winding 2 of the power transformer 3 and another winding it connected across the load circuit 1 by means of a suitable phase shifter it of any suitable type, examples or which are well known in the art, so that the voltage induced in the winding 15 is displaced degrees, or approximately this amount, from the voltage across the load circuit i. The ratio or voltage transformation oi the transformer 33, as well as the direction of the in duced voltage, are changed in a well known manner by varying the position of one of the windings thereof relative to the other winding by means oi? a reversible motor 53;

While I have shown separate transforming means 3 and ii for respectively varying the relative magnitude and phase relation oi the voltages 01 the circuits 3 and 8, it will be evident to those skilled in the art that a single transformer such as shown in United States Letters Patent Nos. 1,722,181 and 1,745,159 and assigned to the assignee of this application may be employed to Vary the relative magnitude and phase relation of the voltages.

As shown in the drawing, the circuit breaker 5 is of the well-known latched closed type having a latch i9 i'or holding the circuit breaker in its closed position, a trip coil 20 for releasing the latch when it is desired to eflect an opening 01' the circuit breaker, and a closing coil 2i which, when energized, eilects the closing of the circuit-breaker. The energizing circuit for the trip coil 2| breaker when it is open and the load circuit l is not energized, I provide suitable automatic reclosing means 25 which is arranged to effect the completion of an energizing circuit for the closing coil 2| of the circuit breaker 5 when the circuit breaker is open and the load circuit voltage is below a predetermined value so that the contacts 26 of 'a voltage relay 21, which is responsive to the voltage across the load circuit l, are closed. Since such automatic reclasing means are well known in the art and the details thereof form no part of my present invention, I have represented the automatic reclosing means 25 by a suitably labeled rectangle.

For effecting the closing of the circuit breaker 5 when it is open and the load circuit is energized at some other point so that the contacts 26 oi the load circuit voltage relay 2'! are open, I

provide a suitable automatic synchronizer 28 ply circuit and load circuit terminals of the (ircuit breaker 5 are less than predetermined values. Since such automatic synchronizers are well known in the art and the details thereof form no part of my present invention, I have represented the automatic synchronizer 28 by a suitably labeled rectangle.

In order to bring the magnitude and phase diiferenceaof these voltages within these predetermined values while the circuit breaker 5 is open and the load circuit is energized, I provide, in accordance with my invention, suitable means for adjusting the transformers 3 and I3 in the proper manner to accomplish this result. In the particular embodiment of my invention shown in the drawing, I provide an arrangement which, after the circuit breaker 5 has been open for a predetermined time, first adjusts the transformer i3 to establish the desiredphase relation between the voltages of the circuit 6 and the winding 4 of the transformer 3 in the circuit I and is arranged to be completed by the contacts 22 when the secondary voltage of the transformer 31 lags the secondary voltage of the transformer 33. The relay 33, when energized, is arranged to complete an operating circuit for the motor |8 so as to cause it to rotate in a direction to effect a decrease in the lag of the load circuit voltage, with respect to the supply circuit voltage, at the point where the circuit breaker 5 is located, and the relay 35, when energized, is arranged to complete an operating circuit for the motor I8 so as to cause it to rotate in the opposite direction and thereby effect a decrease in the lead of the load circuit voltage relative to the supply circuit voltage at the point where the circuit breaker 5 is located. A control relay 38 is connected in parallel with the armature winding of the motor l8 and is provided with suitable contacts in the circuits of the automatic reclosing means 25 so as to render the automatic reclosing means inoperative to effect a reclosure of the circuit breaker 5 while the transformer I3 is being adjusted.

Whenthe control relays 33 and 35 are simultaneously deenergized thereby indicating that there is no need of adjusting the transformer l3 and, therefore, the circuit voltages at the opposite ends of the open circuit breaker 5 are in phase, the transformer 3 is then adjusted to equalize the magnitudes of the two voltages. This result is accomplished by means of a voltage differential relay 39 which, when the voltage of the supply circuit 6 exceeds the voltage of the transformer winding 4, closes its contacts 40 and completes an operating circuit for the motor i so as to cause it to rotate in the'proper direction to increase the voltage of the transformer windin 4. In order to insure that the magnitude of the voltage of the transformer winding 4 is lower than the magnitude of the supply circuit voltage at the time the differential relay 39 is rendered operative to control the adjustment of the transformer 3, I provide an arrangement for controlling the circuit of the motor I in the embodiment shown in Fig. 1, so that this motor ii is operated to effect the adjustment of the transformer 3 to its minimum voltage position when the circuit breaker 5 is open and the time relay 30 is in its deenergized position. A suitable control relay 42 is connected in parallel with the armature winding of the motor H and is provided with suitable contacts in the circuits of the automatic reclosing means 25 so then adjusts the transformer 3 to establish the desired magnitude relation between these voltages as long as the desired phase relation is maintained. This particular arrangement includes a time relay 30, which is set into operation by the opening of the circuit breaker 5, and a phase responsive relay 3|, which is arranged to close its contacts 32 and complete an energizing circuit for an associated control relay 33 when a predetermined phase relation exists between the voltages of the circuit 5 and the transformer winding 4 and to close its contacts 34 and complete an energizing circuit for an associated relay 35 when a different predetermined phase relation exists between these voltages. For the purpose of this description, it will be assumed that the relay 3| is so connected to the circuits 6 and the transformer winding 4 by the isolating transformers 35 and 31, respectively, that the contacts-32 are closed when the secondary voltage of the transformer 31 leads the secondary voltage of the transformer 33 and the contacts 34 are closed as to render this automatic reclosing meansinoperative to effect a reclosure of the circuit breaker 5.while the transformer 3 is being adjusted.

The operation of the embodiment of my invention shown in Fig. 1 is as follows: When the circuit breaker-5 is closed and the supply circuit 6 is supplying current to the load circuit I under normal load conditions, the various control devices are in the positions in which they are shown in the drawing. The motor H for the adjustable transformer 3 may be controlled in any suitable manner, not shown but well known to those skilled in the art, so that the voltage of the load circuit is maintained at a predetermined value.

Upon the occurrence of a fault which causes the fault responsive means 23 to close its contacts 22, an energizing circuit is completed for the trip coil 20 through the auxiliary contacts 44 of the circuit breaker 5 to effect the opening of the circuit breaker and the disconnection of the supply circuit 6 from the load circuit The closing of the contacts 43 of the circuit breaker 5 connects the secondary winding of the isolating transformasearsr erIItotheautomaticsynehroniser II, thephase responsive relay II and the voltage differential relay II to render them operative in accordance witl: the voltage across the transformer wind- 88 If the fault also effects the disconnection of all the voltagerelay II to close its contacts II and complete a starting circuit for the automatic reclosing means II throughthe contacts II of the circuit breaker I, the contacts II of the relay If,

t for the control relay II through II of the circuit breaker I, the conrelay II, and the contacts II of 'lhe closing of the contacts II of coil II to effect the reclosing of the Ii', however, the load circuit I is energized from some other source, such as I, after the circuit a reclosure of the circuit breaker I and by maintaining its contacts I! closed establishes through contacts II of the circuit breaker I an energizing circuit. for the time relay Ill. Before the time relay II, however, completes its timing operation, a circuit is completed for the motor II or the adjustable transformer I through the contacts II of the circuit breaker I, the contacts II of the relay II, the contacts II of the relay II, the limit switch II of the transformer I, and the field winding II and the armature winding of the motor II to cause the motor II to move the adiustable transformer I to its minimum voltage position, in which position the limit switch II is open. when the time relay II completes its timing operation, it opens its contacts II and closes its contacts II. The closing of the contacts II renders the phase responsive relay II operative to control the adjustable transformer II. If the phase relation of the supply and load circuit voltages is such that the secondary volta e of the transformer II leads the secondary voltage of the transformer II and the contacts I2 of the relay II are closed, an energizing circuit is completed for the control relay II through the contacts II of the circuit breaker I and the contacts II of the relay II. If, however, the phase relation of the supply and load circuit voltages is such that the secondary voltage of the transformer II less the secondary voltage of the transformer II and the contacts II of the relay II are closed, an energizing circuit is completed for the control relay II through the contacts II of the circuit breaker I and the contacts II of the relay II. If the supply circuit and load circuit voltages are in phase. the contacts I2 and II of the relay II are both open so that the relays II and II are simultaneously deenergized.

when the relay II is energized. a circuit is completed for the motor II through the contacts II of the circuit breaker I, the contacts II of the relay II, the contacts II of the relay II, the contacts" of the relay II, the limit switch II, and the field winding II and armature winding of the motor II so that the transformer II is adiustedto e the phase of the load circuit voltage so as to decrease the phase diii'erence of.

the secondary voltages of the isolating transform- II completes an energizing circuit for a e of the transformer II.

ersII andI'I. WhentherelayIIisenergised, a circuit is completed for the motor II through the contacts II of the circuit breaker I, the contacts II of the relay II, the contacts II of the relay II, the contacts II of the relay II, the limit switch II, and the field winding I4 and armature winding of the motor II so that the transformer II is adjusted to change the phase of the load circuit voltage so as to decrease the phase difference of the secondary voltages of the isolating transformers II and 31. While the motor II is in operation the relay II, which is connected in parallel with the armature winding of the motor II, maintains its contacts 41 and II open, thereby preventing operation of the automatic reclosing means II.

From the vector diagram shown in Fig. I, it will be evident how the desired phase relation of the secondary voltages of the transformers II and II is obtained by diusting the transformer II under the control of the phase responsive relay II. In this Fig. 3, the vector Il' represents the secondary voltage of the transformer I1, and the vector II represents a secondary voltage of the transformer II lagging the secondary volt- The vector II is shown as being the resultant of a vector I representing the voltage supplied to the load circuit by the source I and a vector II representing the induced voltage of the transformer II and leading the source voltage 'I by degrees. The phase responsive. relay II is so arranged that when the vector II lags the vector II, the relay II by energizing the relay II causes the transformer II to be adjusted so as to increase the length of the vector II until the vectors II and I1 coincide.

In Fig. 3, I have also shown a vector II" which represents a secondary voltage of the transiormer II that leads the secondary voltage of the transformer I1 and which is the resultant of a vector 1" representing the voltage applied across the load circuit I by the source I and a vector I3" representing the induced voltage of th transformer II and lagging the source voltage 7 by 90 degrees. Since the vector II" leads the vector 31', the phase responsive relay II eilects the energization of the control relay II and thereby causes the transformer II to be adjusted so as to increase the length of the vector II" until the vectors II" and Il' coincide.

When the transformer II has been adjusted so that the secondary voltages of the transformers II and II are in phase and the control relays II and II are simultaneously deenergized, a circuit is completed for the motor II through the contacts II of the circuit breaker I, the contacts II of the relay II, the contacts II of the relay III, the contacts II of the relay II, the contacts II of the relay II, the contacts II of the relay 38, the limit switch II, and the field winding 69 and armature winding of the motor II. This circuit causes the motor II to adjust the transformer I in such a manner as to increase the magnitude of the secondary voltage of the transformer II until it is equal to the voltage of the secondary winding of the transformer 31. The automatic synchronizer II may then close its contacts II and complete, through the contacts II of the circuit breaker I, an energizing circuit for the control relay II which, in turn, by closing its contacts II, completes an energizing circuit for the closing coil II to close the circuit breaker I.

The increase in voltage by the operation of mechanism 9, in efiect increases the length of vector 1' or 1'' only. If this operation takes place after 36' or 3B" coincides with 81', and without the subsequent operation of automatic synchronizer 28, relays ll and 40 will repeat the abovementioned operations until vectors 38' or N" and II are within the operating range of relay 2|. While the motor II is in operation a circuit is also completed for the relay 42 which is connected in parallel with the armature winding of the motor H so that the contacts 48 and I interrupt the control circuits to the automatic reclosing means 25.

In the modification of Fig. 1 shown in Fig. 2, I have illustrated an arrangement for effecting thephase adjustment of the secondary voltage of the transformer 36 without first reducing the magnitude thereof to a predetermined value. This result is accomplished by omitting the contacts i! of the relay ll (shown in Fig. 1) and connecting the circuit of the field winding I! and armature winding of the motor Ii so that it includes the contacts ll of the circuit breaker I, the contacts 5| of the relay 4!, the contacts IQ of the relay in, the contacts 68 of the relay 33, the contacts 61 of the relay 3!, and the contacts ll of the relay 3! which are closed when the magnitude of the secondary voltage of the transformer 36 is greater than the magnitude of the secondary voltage of the transformer 31. Therefore, it will be seen that in the modification shown in Fig. 2 the transformer 3 is not adjusted until after the circuit breaker I has been open for a suiilcient length of time to pick up the relay 30 and the phase adjustment has been made so as to bring the secondary voltages of the transformers 36 and 31 into phase. Then, the transformer 3 is adjusted under the control of the voltage differential relay :0 to equalize the magnitudes of the secondary voltages of the transformers 38 and 31.

While I have, in accordance with the Patent Statutes, shown and described my invention as applied to a particular system and as embodying vairousv devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art, and I therefore aim said voltages,

3. In combination, two energized alternating current circuits, a circuit breaker for interconnecting said circuits, adjustable transforming means for varying the magnitude and phase relation of the circuit voltages on opposite sides of said circuit breaker, means controlled by said voltages for adjusting said transforming means so as to establish a predetermined magnitude and phase relation between said voltages, and means responsive to said predetermined magnitude and phase relation between said voltages for closin said circuit breaker.

4. In combination, two energized alternating current circuits, a circuit breaker interconnecting said circuits, fault responsive means for effecting the opening of said circuit breaker, adjustable transforming means in one of said circuits for varying the phase relation of the voltages of the disconnected circuits, means responsive to the opening of said circuit breaker for controlling said transforming means in response to the phase relation of said voltages so as to establish a predetermined phase relation of said voltages, and automatic synchronizing means controlled by the phase relation for closing said circuit breaker.

5. In combination, two energized alternating current circuits, a circuit breaker interconnecting said circuits, fault responsive means for effecting the opening of said circuit breaker, ad-

of said voltages justable transforming means in one of said cir cults for varying the phase relation of the voltages of the disconnected circuits, means responsive to the opening of said circuit breaker for controlling said transforming means in response to the phase relation of said voltages so as to establish a predetermined phase relation of said voltages, means responsive to the establishment of said predetermined phase relation of said voltages for controlling said transforming means to establish a predetermined magnitude relation of and automatic synchronizing means controlled by the phase and magnitude relation of said voltages for closing said circuit in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

i. In combination, two' energized alternating current circuits, adjustable transforming means for varying the magnitude of the voltage at a predetermined point of one of said circuits and for varying the phase relation between said voltage and a voltage at a predetermined point of the other circuit, and means controlled by said voltages for automatically adjusting said transform ing means so as to establish a predetermined magnitude and phase relation between said voltages.

2. In combination, two energized alternating current circuits, a circuit breaker for interconnecting said circuits, adjustable transforming means for varying the voltage at a predetermined point of one of said circuits and for varying the phase relation between said voltage and a voltage at a predetermined point of the other circuit, means controlled by said voltages for adjustin said transforming means so as to establish a predetermined magnitude and phase relation between said voltages, and means responsive to said predetermined magnitude and phase relation between said voltages for closing said circuit breaker.

breaker.

6.'In combination, two energized alternating current circuits, a circuit breaker interconnecting said circuits, fault responsive means for effecting the opening of said circuit breaker, ad-

justable transforming means in one of said oil'- cuits for producing therein a variable voltage displaced a predetermined amount from the voltage across said circuit, means responsive to the opening of said circuit breaker for controlling said transforming means in response to the phase relation of the circuit voltages on opp site sides of said circuit breaker for establishing a predetermined phase relation of said circuit voltages, and automatic synchronizing means controlled by,the phase relation of said circuit voltages for closing said circuit breaker.

'7. In combination, two energized alternating current circuits, a circuit breaker interconnecting said circuits, fault responsive means for effecting the opening of said circuit breaker, adiustable transforming means in one of said circuits for producing therein a variable voltage displaced a predetermined amount from the voltage across said circuit, means responsive to the opening of said circuit breaker for controlling said transforming means in response to the phase relation of the circuit voltages on opposite sides of said circuit breaker for establishing a predetermined phase relation of said circuit voltages, other adjustable transforming means in one of said circuits for varying the relative magnitudes of the circuitvoitages on opposite sides of said circuit breaker. means responsive to the establishment of said predetermined phase relation of said circuit voltages for controlling said other adjustable transforming means to establish a predetermined magnitude relation of said-voltages, and automatic synchronising means controlled by the phase and magnitude relation of said circuit voltages for closing said circuit responsive to the opening of said circuit breaker and the voltage of said predetermined one of said circuits being above a predetermined value for controlling said transforming means in response to the phase relation of said circuit voltages to establish a predetermined phase relation of said circuit voltages, and automatic synchronizing means controlled by the phase relation of said circuit voltage for closing said circuit breaker.

9. In combination, two energized alternating current circuits, a circuit breaker interconnecting said circuits, fault responsive means for effecting the opening of said circuit breaker, adjustable transforming means in one of said circuits for varying the phase relation of the voltages of said circuits, means responsive to the opening of said circuit breaker and the voltage of a predetermined one of said circuits being below a predetermined value for effecting the reclosure of said circuit breaker independently of the phase relation of said circuit voltages, means responsive to the opening of said circuit breaker and the voltage of said predetermined one of said circuits being above a predetermined value for controlling said transforming means in response to the phase relation of said circuit voltages to establish a predetermined phase relation of said circuit voltages, means responsive to the establishment of said predetermined phase relation of said circuit voltages for controlling said transforming means to establish a predetermined magnitude relation of said voltages, and automatic synchronizing means controlled by the phase and magnitude relation of said voltages for closing said circuit breaker.

10. In combination, two energized alternating current circuits, a. circuit breaker interconnect ing said circuits, fault responsive means for effooting the opening of said circuit breaker, adiustable transforming means in one of said circuits for varying the phase relation of the voltages of said circuits, means responsive to the opening of said circuit breaker and the voltage of a predetermined one of said circuits being below a predetermined value for effecting the reclosure of said circuit breaker independently of the phase relation of said circuit voltages, means ages to establish a predetermined phase relation of said circuit voltages, other transforming means in one of said circuits for varyingthe magnitude of the voltage thereof, means responsive to said predetermined phase relation of said circuit voltages i'or controlling said other transforming means to establish a predetermined magnitude relation of said circuit voltages, and automatic synchronizing means controlled by the phase and magnitude relation of said circuit voltages for closing said circuit breaker.

11. In combination, two energized alternating current circuits, a circuit breaker interconnecting said circuits, fault responsive means for eiiecting the opening of said circuit breaker, adjustable transforming means in one of said circuits for varying the phase and magnitude relation of the voltages of said circuits, means responsive to the opening of said circuit breaker for eifecting the' operation of said transforming means to decrease the magnitude of the associated circuit voltage and then the operation of said transforming means to establish a predetermined phase rclation of the voltages of said circuits, means responsive to the establishment of said predetermined phase relation of said voltages for controlling said transforming means to establish a predetermined magnitude relation of said circuit voltages, and automatic synchronizing means controlled by the phase and magnitude relation Iof said circuit voltages for closing said circuit rea er.

12. In combination, two energized alternating current circuits, a circuit breaker interconnecting said circuits, fault responsive means for effecting the opening of said circuit breakeig'adiustable transforming means in one-of said circuits for varying the phase and magnitude relation of the voltages of said circuits, means responsive to the opening of said circuit breaker and the voltage of a predetermined one of said circuits being below a predetermined value for effecting the reclosure of said circuit breaker independently of the phase relation of said circuit voltages, means responsive to the opening of said circuit breaker and the voltage of said predetermined one of said circuits being above a predetermined value for effecting the operation of said transforming means to decrease the magnitude of the associated circuit voltage and then the operation of said transforming means to es: tablish a predetermined phase relation of the voltages of said circuits, means responsive to the establishment of said predetermined phase relation of said voltages for controlling said transforming means to establish a predetermined magnitude relation of said circuit voltages. and automatic synchronizing means controlled by the phase and magnitude relation of said circuit voltages for closing said circuit breaker.

13. In combination, two energized alternating current circuits, a circuit breaker interconnecting said circuits, fault responsive means for effecting the opening of said circuit breaker, adjustable transforming means in one of said circuits for varying the phase relation of the voltages of said circuits, means responsive to the opening of said circuit breaker and the voltage of a predetermined one of said circuits being below a predetermined value for effecting the reclosure of said circuit breaker independently of the phase relation of said circuit voltages, other transforming means in one of said circuits for varying the magnitude of the voltage thereof, means responsive to the opening of said circuit breaker and the voltage or said predetermined one of said circuits being above a predetermined value 'i'or first effecting the operation of said other transforming means to decrease the ma nitude of the associated circuit voltage and then the operation of said first mentioned transforming means to establish a predetermined phase relation of said circuit voltages, means responsive to said predetermined phase relation of said circuit voltages for controlling said other transforming means to establish a predetermined magnitude relation of said circuit voltages, and automatic synchronizing means controlled by the phase and magnitude relation 0: said circuit voltages for closing said circuit breaker.

- ARVID E. ANDERSON. 

